This invention is related to the field of digital image signal processing, and more particularly to a system for processing hierarchical video data.
An objective in the development of digital video encoding and decoding formats has been to provide a standard that accommodates different video transmission and reception systems. A further objective has been to promote interoperability and backward compatibility between different generations and types of video encoding and decoding equipment. In order to promote such interoperability and compatibility, it is desirable to define encoding and decoding strategies which can accommodate different types of video image scan (e.g. interlaced/progressive), frame rate, picture resolution, frame size, chrominance coding, and transmission bandwidth.
One strategy used to achieve interoperability involves separating video data into one or more levels of a data hierarchy (layers) organized as an ordered set of bitstreams for encoding and transmission. The bitstreams range from a base layer, i.e. a datastream representing the simplest (e.g. lowest resolution) video representation, through successive enhancement layers representing incremental video picture refinements. The video data is reconstructed from the ordered bitstreams by a decoder in a receiver. This strategy permits decoder complexity to be tailored to achieve the desired video picture quality. A decoder may range from the most sophisticated configuration that decodes the full complement of bitstreams, that is all the enhancement layers, to the simplest that decodes only the base layer.
A widely adopted standard that uses such a data hierarchy is the MPEG (Moving Pictures Expert Group) image encoding standard (ISO/IEC 13818-2, May 10th 1994), hereinafter referred to as the xe2x80x9cMPEG standardxe2x80x9d. The MPEG standard details how the base and enhancement layer data may be derived, and how the video data may be reconstructed from the layers by a decoder. It is herein recognized that it is desireable to provide a system that incorporates encoder and decoder architectures for rationally partitioning data between the various layers and for dynamically configuring such a system for this purpose.
In accordance with the principles of the present invention, dynamically configurable video signal processing systems enable data allocation among hierarchical layers to be varied. The dynamically configurable systems also permit the data to be partitioned between the hierarchical layers as desired, and allow variation in the number of layers employed.
A disclosed digital signal processing system according to the present invention adaptively processes a datastream of image representative input data. A data processor automatically partitions input data into one or more hierarchical layers as a function of one or more parameters selected from available system bandwidth, input data rate, and output signal quality.
Also disclosed is a digital signal processing system for adaptively decoding a datastream of image representative input data partitioned into one or more hierarchical layers. The decoding system derives synchronization and configuration information from the input data and is adaptively configured to decode the number of hierarchical layers of the input data in response to a locally generated Control signal.
In accordance with a feature of the invention, the image resolution and corresponding number of pixels per image is varied as a function of system parameters.